1. Field of the Invention
This invention relates to a semiconductor photodetector device, and particularly to a side-illuminated type semiconductor photodetector device suitable for use in surface hybrid integration for 1 xcexcm-band optical communications.
2. Description of the Related Art
As one of conventional end-face light incidence type semiconductor photodetector devices, there is known one disclosed in Japanese Patent Application Laid-Open No. Hei 9-307134.
In FIG. 3 shown in the above-described publication, an optical module has been disclosed which reflects light incident to an end face of an n type InP substrate 3 from within the atmosphere and propagated through the n type InP substrate 3 by a metal layer 15 (mirror reflective film) having a high reflectance, which is formed over a slanting surface 3A of the n type InP substrate 3, thereby introducing the light into a photodetecting unit or photodetector PD.
Even if, for example, Au relatively high in reflectance is used as the metal layer 15 at an interface between the metal layer 15 and the InP substrate in the above-described publication, the reflectance would become about 0.6 where the wavelength of light is given as 1.3 xcexcm (corresponding to the wavelength of light normally used in the end-face light incidence type semiconductor photodetector device) and the angle of incidence of the light is given as 55xc2x0. At this time, a photoelectric current corresponding to the incident light results in 0.6 A/W and hence sensibility is reduced. Since Au is very poor in adhesion to the InP substrate, it peels off immediately.
When chromium or titanium excellent in adhesion to the InP substrate is used as the metal layer 15, its reflectance is further lowered as compared with Au.
Thus, when the metal layer is used as the mirror reflective film as in the above-described publication, it was not possible to simultaneously satisfy the merits of adhesion and reflectance (in the case of light having the wavelength of 1.3 xcexcm).
According to the above-described publication, when the InP substrate kept in a wafer state is flawed by a diamond after a V groove has been defined in the InP substrate, and an end face of the InP substrate is formed by cleavage, stress is concentrated on the V groove and hence the InP substrate is cleaved along the V groove, whereby the end face is formed at a position different from the designed position. Further, a chip itself is brittle against stresses applied from the upper surface and back side thereof.
With the foregoing in view, it is therefore an object of the present invention to provide a semiconductor photodetector device capable of simultaneously satisfying the merits of adhesion and reflectance.
Another object of the present invention is to improve a manufacturing yield of a semiconductor photodetector device wherein a semiconductor substrate with a V groove defined therein is formed by cleavage.
In order to achieve the above objects, there is provided a semiconductor photodetector device according to the present invention, comprising a semiconductor substrate provided with a slanting surface, a material lower in refractive index than the semiconductor substrate, which is formed over the slanting surface as a reflective film, and a photodetecting unit formed over the semiconductor substrate, for reflecting light incident to the semiconductor substrate by the slanting surface and introducing it therein, and wherein the material is an insulating film and the angle of incidence of the light to each of the insulating film having a predetermined refractive index and the slanting surface is set so that the reflection is brought to total reflection.
The present invention further includes various inventions to achieve the above objects.
These inventions will become apparent from the appended claims and the following embodiments.